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Grzegorz Markiewicz, Dawid Pakulski, Agostino Galanti, Violetta Patroniak, Artur Ciesielski, Artur R Stefankiewicz, Paolo Samorì
The functionalization of a spherical Keplerate-type polyoxometalate {Mo72V30} with a cationic azobenzene surfactant has been achieved through ionic self-assembly. The photoisomerisation reaction of this complex, which emerges in a light-triggered aggregation-disaggregation process, has been followed by (1)H NMR spectroscopy, dynamic light scattering, absorption spectroscopy and scanning electron microscopy analyses.
April 20, 2017: Chemical Communications: Chem Comm
Gongutri Borah, Preetismita Borah, Pitambar Patel
Cp*Co(iii)-catalyzed C-H amidation of azobenzene with dioxazolones has been developed. The amidation reaction does not require external oxidants and gives carbon dioxide as the only by-product. Both symmetrical and unsymmetrical azobenzenes were found to undergo amidation smoothly with broad functional group tolerance.
April 19, 2017: Organic & Biomolecular Chemistry
Han Na Joo, Thuy Van Thi Nguyen, Hyeon Kyeong Chae, Young Jun Seo
In this study, we synthesized an Azo-py phosphoramidite, featuring azobenzene and pyrene units, as a novel fluorescent and isomeric (trans- and cis-azobenzene units) material, which we incorporated in an i-motif DNA sequence. We then monitored the structural dynamics and changes in fluorescence as the modified DNA sequences transformed from single strands at pH 7 to i-motif quadruplex structures at pH 3. After incorporating Azo-py into the 4A loop position of an i-motif sequence, dramatic changes in fluorescence occurred as the DNA structures changed from single-strands to i-motif quadruplex structures...
April 6, 2017: Bioorganic & Medicinal Chemistry Letters
Marina Juribašić Kulcsár, Ivan Halasz, Ana Budimir, Krunoslav Užarević, Stipe Lukin, Andrea Monas, Franziska Emmerling, Janez Plavec, Manda Ćurić
N-H bond activation of gaseous ammonia is achieved at room temperature in a reversible solvent-free reaction using a solid dicyclopalladated azobenzene complex. Monitoring of the gas-solid reaction in real-time by in situ solid-state Raman spectroscopy enabled a detailed insight into the stepwise activation pathway proceeding to the final amido complex via a stable diammine intermediate. Gas-solid synthesis allowed for isolation and subsequent structural characterization of the intermediate and the final amido product, which presents the first dipalladated complex with the Pd(II)-(μ-NH2)-Pd(II) bridge...
April 17, 2017: Inorganic Chemistry
Hiromi Takahashi, Kyoko Fujita, Hiroyuki Ohno
The adsorption-desorption equilibrium of sublimed molecules has been analyzed dynamically by optical waveguide (OWG) spectroscopy. Dynamic change of the transition moment during adsorption behavior was successfully detected using polarized incident light. With this technique, sublimed planer aromatic molecules, such as azobenzene, were revealed to stack parallel to the solid surface at the initial stage followed by adsorption with relatively random orientation.
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Jie Wu, Yun Xu, Dengfeng Li, Xiang Ma, He Tian
The host-guest interaction based on thiol-β-cyclodextrin and a symmetric compound containing two azobenzene units on ends has been utilized to form end-to-end assembly of gold nanorods. Both UV light irradiation and guest competition can be used to transform the GNR alignments in a disassembled manner.
April 20, 2017: Chemical Communications: Chem Comm
Erin Bailey, Ribal Georges Sabat
Large-scale linear diffraction gratings with gradually varying pitch were photo-inscribed onto the surface of azobenzene thin films using a 532 nm laser and a modified Lloyd mirror set-up. By placing a cylindrical lens in front of the direct half of the inscribing beam, gratings with a chirping rate as high as 12.9 nm/mm were produced. Subsequently, when these chirped-pitch gratings were coated with silver, over three-fold bandwidth increase was observed in the surface plasmon transmission peaks at FWHM, when compared to constant-pitch gratings...
March 20, 2017: Optics Express
Yue Shi, Chenxiang Zhao, Jacob Yeuk-Lung Ho, Valery V Vashchenko, Abhishek Kumar Srivastava, Vladimir G Chigrinov, Hoi-Sing Kwok, Feng Song, Dan Luo
Azobenzene photoalignment materials are highly effective for liquid crystal alignment with high sensitivity and rewritability. A strong relationship between relative humidity and the alignment quality of a thin layer of azobenzenesulfonic dye has been investigated, where the photoinduced phase retardation, order parameter, and anchoring strength of the alignment layer are influenced dramatically by relative humidity. Our results provide fabrication guidance for the photoalignment process in both display and photonic applications...
April 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Kai Müller, Alexander Knebel, Fangli Zhao, David Bléger, Jürgen Caro, Lars Heinke
Stimuli-responsive molecules change their properties when exposed to external signals, such as light, and enable the preparation of smart materials. UV light, which often destroys organic materials, is typically required for activating the desired response of photoswitchable compounds, significantly limiting the potential applications of light-operated smart materials. Herein, we present the first metal-organic framework (MOF), which enables reversible modulation of key properties upon irradiation with visible light only...
April 24, 2017: Chemistry: a European Journal
Michael J Landry, Matthew B Applegate, Oleksandr S Bushuyev, Fiorenzo G Omenetto, David L Kaplan, Mark Cronin-Golomb, Christopher J Barrett
Azobenzene modification of Bombyx mori silkworm silk creates a photo-responsive 'azosilk' biomaterial, allowing for 3D laser patterning. Written regions fluoresce, and become fluid-filled raised 'micro-blisters' with a 10-fold photo-softening effect of the modulus. Patterning is facile and versatile, with potential applications as soft tunable materials for dynamic cell guidance and microfluidics.
April 19, 2017: Soft Matter
Marco Saccone, Antti Siiskonen, Franisco Fernandez-Palacio, Arri Priimagi, Giancarlo Terraneo, Giuseppe Resnati, Pierangelo Metrangolo
Crystals of trans- and cis-isomers of a fluorinated azobenzene derivative have been prepared and characterized by single-crystal X-ray diffraction. The presence of F atoms on the aromatic core of the azobenzene increases the lifetime of the metastable cis-isomer, allowing single crystals of the cis-azobenzene to be grown. Structural analysis on the cis-azobenzene, complemented with density functional theory calculations, highlights the active role of the halogen-bond contact (N...I synthon) in promoting the stabilization of the cis-isomer...
April 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
Xue Tian, Chao Zhang, Qi Xu, Zhong Li, Xusheng Shao
Benzoylphenylureas (BPUs) are used as synthetic insect growth regulators for inhibiting chitin synthesis. Merging insecticidal BPUs with photoswitchable azobenzene generated photoresponsive chitin synthesis inhibitors. A prepared azobenzene-benzoylphenylurea can be activated upon irradiation with UV light, and shows 6-fold and 2-fold activity difference to armyworm (Mythimna separata) and German cockroach (Blattella germanica) sulfonylurea receptors, respectively. This is the first example of a photoswitchable BPU insecticide...
April 11, 2017: Organic & Biomolecular Chemistry
Carla Pernpeintner, James A Frank, Patrick Urban, Christian R Roeske, Stefanie D Pritzl, Dirk Trauner, Theobald Lohmüller
Giant unilamellar vesicles (GUVs) represent a versatile model system to emulate the fundamental properties and functions associated with the plasma membrane of living cells. Deformability and shape transitions of lipid vesicles are closely linked to the mechanical properties of the bilayer membrane itself and are typically difficult to control under physiological conditions. Here, we developed a protocol to form cell-sized vesicles from an azobenzene-containing phosphatidylcholine (azo-PC), which undergoes photoisomerization on irradiation with UV-A and visible light...
April 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Shaoyu Chen, Yanyan Zhang, Kunlin Chen, Yunjie Yin, Chaoxia Wang
A photoresponsive surfactant of 4-octoxy-4'-[(trimethylamino)ethoxy]azobenzene (OTAEAzo) has been synthesized for developing a fast-phototuning foam switch based on its high sensitivity, reversibility, and fatigue resistance of the photoisomerization capability. Ultraviolet (UV)-light irradiation for 1 s enabled conversion from the trans isomer to the cis configuration, while exposure to visible (Vis)-light for 3 min induced a cis-to-trans transformation, which maintains an excellent cycling stability for 20 cycles of photoisomerization...
April 4, 2017: ACS Applied Materials & Interfaces
Vladimir Toshchevikov, Tatiana Petrova, Marina Saphiannikova
Azobenzene-containing smart materials are able to transform the energy of light into directional mechanical stress. We develop a theory of time-dependent light-induced ordering and deformation in azobenzene materials starting from the kinetic equations of photoisomerization. The liquid crystalline (LC) interactions between rod-like trans-isomers are taken into account. Angular selectivity of the photoisomerization known as an "angular hole burning" or the Weigert effect leads to the light-induced ordering and deformation of the azobenzene materials...
April 12, 2017: Soft Matter
Koichiro Beppu, Yuki Nagashima, Mituo Hara, Shusaku Nagano, Takahiro Seki
The microphase separation and photoalignment behavior of a diblock copolymer consisting of two kinds of side chain liquid crystalline (LC) polymers are investigated. Here, the mesogens of photoresponsive azobenzene and non-photoresponsive cyanobiphenyl are introduced in the side chains. The azobenzene and cyanobiphenyl mesogens orient homeotropically and planarly, respectively, in a thin film state. The combination of these contrasting orienting properties leads to a formation of vertically oriented lamella in the microphase separation structure...
March 24, 2017: Macromolecular Rapid Communications
Li-Rong Lin, Hui-Hui Tang, Yun-Guang Wang, Xuan Wang, Xue-Ming Fang, Li-Hua Ma
The coordination ability of ligands functionalized by azobenzene was manipulated, and two novel chelating ligands, (E)-4-(phenyldiazenyl)-N,N-bis(pyridin-2-ylmethyl) benzohydrazide (C25H22N6O, PBPM) and (E)-4-((4-(dimethylamino)phenyl)diazenyl)-N,N-bis(pyridin-2-ylmethyl) benzohydrazide (C27H27N7O, dmPBPM), were synthesized. The ligands can offer four coordinating atoms (one oxygen and three nitrogens) to act as tetradendate ligands, together with the two β-diketonates (4,4,4-trifluoro-1-phenylbutane-1,3-dionate, tfd), and the trifluoroacetate anion presented as a ligand and a counterion to form the quaternary units with lanthanide(III) ions (La, Eu, and Gd), [Ln(tfd)2(PBPM)(CF3CO2)] (LnC47H34F9N6O7) and [Ln(tfd)2(dmPBPM)(CF3CO2)] (LnC49H39F9N7O7), where the lanthanide(III) ions are nine coordinated with N3O6 donor sets...
March 22, 2017: Inorganic Chemistry
Ivan V Malyar, Evgenii Titov, Nino Lomadze, Peter Saalfrank, Svetlana Santer
We report on photoinduced remote control of work function and surface potential of a silicon surface modified with a photosensitive self-assembled monolayer consisting of chemisorbed azobenzene molecules (4-nitroazobenzene). It was found that the attachment of the organic monolayer increases the work function by hundreds of meV due to the increase in the electron affinity of silicon substrates. The change in the work function on UV light illumination is more pronounced for the azobenzene jacketed silicon substrate (ca...
March 14, 2017: Journal of Chemical Physics
Marthe Ketels, David B Konrad, Konstantin Karaghiosoff, Dirk Trauner, Paul Knochel
A mild and general set of metalation procedures for the functionalization of unsymmetrical azobenzenes using a commercially available continuous-flow setup is reported. The metalations proceed with TMPLi under convenient conditions (0 °C, 20 s), and various classes of electrophiles can be used. With sensitive substrates, an in situ trapping metalation in which TMPLi is added to a mixture of the azobenzene and ZnCl2 or MgCl2·LiCl was very effective for achieving high yields.
April 7, 2017: Organic Letters
Hongwei Zhou, Changguo Xue, Philipp Weis, Yasuhito Suzuki, Shilin Huang, Kaloian Koynov, Günter K Auernhammer, Rüdiger Berger, Hans-Jürgen Butt, Si Wu
The development of polymers with switchable glass transition temperatures (Tg) can address scientific challenges such as the healing of cracks in high-Tg polymers and the processing of hard polymers at room temperature without using plasticizing solvents. Here, we demonstrate that light can switch the Tg of azobenzene-containing polymers (azopolymers) and induce reversible solid-to-liquid transitions of the polymers. The azobenzene groups in the polymers exhibit reversible cis-trans photoisomerization abilities...
February 2017: Nature Chemistry
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